Dual control analog delay element
View Patent ↗An analog delay element for delaying an input clock signal to produce an output clock signal. The analog delay element includes a delay circuit for receiving the input clock signal and for providing an intermediate clock signal in response to a first bias voltage. A current mirror amplifier generates a first current in a first current branch in response to the intermediate clock signal, and generates a second current in a second current branch in response to the first current and a second bias voltage. The second current branch has an output node for providing the output clock signal having a logic level corresponding to the delayed intermediate clock signal logic level.
1. An analog delay element for delaying an input clock signal to produce an output clock signal, the analog delay element comprising:
a delay circuit for receiving the input clock signal and for providing an intermediate clock signal in response to a first bias voltage; and
a current mirror amplifier for generating a first current in a first current branch in response to the intermediate clock signal and for generating a second current in a second current branch in response to the first current and a second bias voltage, the second current branch having an output node for providing the output clock signal having a logic level corresponding to the intermediate clock signal.
2. The analog delay element of claim 1 , wherein the delay circuit includes
a current source for providing a constant current in response to the first bias voltage, and
a clock input circuit receiving the input clock signal and connected in series to the current source at a common terminal for providing the intermediate clock signal.
3. The analog delay element of claim 1 , wherein the first current branch includes a diode connected load transistor connected in series to a first input transistor, the first input transistor gate receiving the intermediate clock signal.
4. The analog delay element of claim 3 , wherein the second current branch includes a load transistor connected in series to a second input transistor at the output node, the diode connected load transistor and the load transistor are arranged in a current mirror configuration and the second input transistor gate receives the second bias voltage.
5. The analog delay element of claim 4 , further including an activating circuit connected to a common node of the first input transistor and the second input transistor for enabling the current mirror amplifier.
6. The analog delay element of claim 5 , wherein the activating circuit receives a third bias voltage.
7. The analog delay element of claim 1 , further including a pull-down circuit for coupling the output node to a first voltage when the input clock signal is at a second voltage.
8. The analog delay element of claim 1 , further including a pull-down circuit for coupling the first current branch and the second current branch of the current mirror amplifier to a first voltage when the input clock signal is at a second voltage.
9. The analog delay element of claim 1 , wherein the first bias voltage is generated by a first bias voltage generator programmable by a first set of signals.
10. The analog delay element of claim 1 , wherein the second bias voltage is generated by a second bias voltage generator programmable by a second set of signals.
11. The analog delay element of claim 1 , wherein the current mirror amplifier includes a biased transistor receiving a third bias voltage, the biased transistor electrically coupling the first current branch and the second current branch to a voltage supply for enabling the current mirror amplifier to delay the output clock signal from being provided at the output node when the input clock signal is at a first logic level.
12. The analog delay element of claim 11 , further including a bypass transistor electrically coupling the first current branch and the second current branch to the voltage supply when the input clock signal is at a second logic level.
13. The analog delay element of claim 11 , further including a disabling circuit for driving the output node to the voltage supply when the input clock signal is at a second logic level.
14. A delay circuit comprising:
a first analog delay circuit for receiving an input clock signal and driving an intermediate output from a first voltage towards a second voltage in a first duration of time in response to a first bias voltage when the input clock signal is at a first logic level; and,
a second analog delay circuit having a first input coupled to the intermediate output and a second input for receiving a second bias voltage, the second analog delay circuit including a current mirror circuit for driving an output from the first voltage towards the second voltage in a second duration of time in response to the second bias voltage when the intermediate output is greater than the second bias voltage.
15. The delay circuit of claim 14 , wherein the first analog delay circuit includes
a load transistor having a gate terminal for receiving the first bias voltage, and,
an input transistor having a gate terminal for receiving the input clock signal, the load transistor and the input transistor being connected in series between the first voltage and the second voltage at the intermediate output.
16. The delay circuit of claim 14 , wherein the current mirror circuit includes
a diode connected load transistor connected in series to a first input transistor, the first input transistor gate corresponding to the first input,
a mirror transistor connected in series to a second input transistor at the output, the mirror transistor gate being connected to the diode connected load transistor gate, the second input transistor gate corresponding to the second input.
17. The delay circuit of claim 14 , wherein the first bias voltage is generated by a first bias voltage generator programmable by a first set of signals.
18. The delay circuit of claim 17 , wherein the second bias voltage is generated by a second bias voltage generator programmable by a second set of signals.
19. The delay circuit of claim 18 , wherein the first set of signals are coarse delay control signals, and the second set of signals are fine delay control signals.